Answer
$[H_3O^+] = 7.586 \times 10^{- 10}M$
$[OH^-] = 1.318 \times 10^{- 5}M$
This is a basic solution.
Work Step by Step
$[H_3O^+] = 10^{-pH}$
$[H_3O^+] = 10^{- 9.12}$
$[H_3O^+] = 7.586 \times 10^{- 10}M$
$[H_3O^+] * [OH^-] = Kw = 10^{-14}$
$ 7.586 \times 10^{- 10} * [OH^-] = 10^{-14}$
$[OH^-] = \frac{10^{-14}}{ 7.586 \times 10^{- 10}}$
$[OH^-] = 1.318 \times 10^{- 5}M$
$[OH^-] > [H_3O^+]$: Basic solution.
Assuming $25^{\circ}C$: pH > 7 : Basic solution.
